Adjective vs Adverb

Question 1

Carbon-14 dating reveals that the megalithic monuments in Brittany are nearly 2,000 years as old as any of their supposed Mediterranean predecessors.
A. as old as any of their supposed
B. older than any of their supposed
C. as old as their supposed
D. older than any of their supposedly
E. as old as their supposedly

Answer 1

In this case, “supposed,” an adjective, modifies the noun “predecessors.” This makes perfect sense. “Supposed” implies that the noun in question is not what it appears to be. If I refer to my friend’s “supposed” wife, I’m implying that they’re not really married. (And maybe guaranteeing that my friend will soon be an ex-friend.) In this case, if the monuments in Brittany are 2000 years older than their “supposed” predecessors, I’m pointing out that the younger monuments are, by definition, not predecessors, contrary to prior belief.

Now, “supposedly” is an adverb and so should modify something other than a noun. It seems to modify the adjective “Mediterranean.” But there’s no reason to doubt that the other artifacts are Mediterranean! We’re doubting that they’re predecessors. Note that it’s the logic and context of the sentence - younger monuments can’t be predecessors to older ones - that dictates which option is better here.